1. Field of the Invention
The present invention is generally concerned with clutch release bearings in which a drive member which is adapted to operate a clutch release device in a clutch, for example a diaphragm spring, and an operating member which is adapted to be operated by a control member, in practice a clutch release yoke, are coupled together in the axial direction but free to rotate relative to one another. The invention is more particularly concerned with clutch release bearings of the aforementioned type in which the operating member comprises at least one arm projecting radially from a body portion, said arm and said body portion respectively having an axial support surface and a radial support surface for said control member.
2. Description of the Prior Art
An axial support surface of this kind is usually constituted by a pad coupled axially to the radial arm of the operating member by a peg, said peg being in practice force-fitted into a hole in said arm provided for this purpose and parallel to the axis of the bearing. The radial support surface is generally obtained by milling an axial or tangential facet into said initially cylindrical body portion, at the base of the radial arm; this facet is then surface-hardened so that it is able, efficiently and without excessive wear, to guide the control member in the axial direction and to block rotation of the operating member by means of the control member. In practice, with a view to optimizing the contact area between the control member and the pad relative to the radial dimension of the latter, said pad is often machined to form a flat which is adapted to cooperate with the aforementioned facet. Thus in this type of bearing the formation of the axial and radial support surfaces involves the execution of milling operations which are significantly more costly than the turning operations which are all that is required to produce the bearings from the original castings.
In another arrangement disclosed in French Patent Application No. 81 17754, the axial and radial support surfaces are constituted by the central leg and a flange of a T-shaped part, the other flange having a hole by means of which said T-shaped part is force-fitted to the radial arm so that it is in contact with the cylindrical body portion. This arrangement eliminates all milling operations and all surface treatment of the operating member. On the other hand, it has a number of disadvantages. Specifically, it results in a non-negligible axial dimension on the side of the radial arm opposite that on which said central leg rests. Also, retained on the radial arm by virtue of its force-fitting thereto, the T-shaped part in practice bears on the body of the operating member, as a a result of which the latter is subject to wear. Further, the aforementioned force-fitting involves extremely accurate dimensioning of said hole and the radial arm.
The objective of the present invention is to overcome the disadvantages of the aforementioned prior art arrangements.